A normal type of binocular comprises a focusing mechanism and a zooming mechanism. When a viewer uses this kind of binocular he or she must operate a focusing member and a zooming member while holding a pair of telescopes. Then, the binocular body is apt to be vibrated due to a certain shaking of either fingers or hands. Thus, an object for viewing is out of focusing and zooming. Particularly, while increasing the magnification by operating the zooming member, it becomes difficult to catch the object exactly. From this point of view, how to enhance the binocular's operability is required in this industry. In order to solve the problem of operability, I have filed a Patent application both in Japan and abroad, wherein a focusing device and a zooming device are mounted in parallel with each other on a center axis between two telescopes. Referring to the prior art which is within the spirit and scope of this invention, the following references can be cited: U.S. Pat. Nos. 4,066,329, 2,988,955, 3,069,972, 2,988,974, etc. However, in any one of the above cited references, there exists no concept that the focusing member and the zooming member are mounted in a tandem form on an axis coupling the two telescopes. In other words, in any one of them a viewer holding a pair of telescopes is obliged to operate the zooming member and the focusing member individually which are disposed separately from each other. In other words, when the above two operating members are mounted tandemly on the center axis coupling the two telescopes, they are easily contacted and simultaneously operated by the user's fingertips while holding a pair of telescopes by both hands. Thus, such a tandem disposition of the two operating members is very natural and suitable in view the finger motion and the proper structure of the binocular.